Breather device for engine

Abstract

In a breather device for engine, in which an inlet of a breather chamber communicates with a crank chamber through a reed valve, the reed valve being formed of: a fixed stopper plate arranged so as to be opposed to a valve seat formed on an end face of the inlet facing the breather chamber; and an elastic valve plate fixed at one end thereof to the stopper plate and capable of bending elastically to change its position from a closed position in which the elastic valve plate closes the inlet by seating on the valve seat to an opening limit position in which the elastic valve plate opens the inlet and abuts against the stopper plate, the stopper plate is provided at a center part thereof with an oil discharge hole through which oil present between the elastic valve plate and the stopper plate is pushed out when the elastic valve plate is pushed toward the opening limit position in which the elastic valve plate abuts against the stopper plate by pressure in the crank chamber. Accordingly, it is possible to prevent the elastic valve plate from sticking to the stopper plate even if oil mist adheres to the elastic valve plate or the stopper plate of the reed valve.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present invention claims priority under 35 USC §119 based on Japanese patent application No. 2008-147722 filed Jun. 5, 2008. The subject matter of this priority document is incorporated by reference herein.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an improvement of a breather device for engine, in which an inlet of a breather chamber communicates with a crank chamber of an engine through a reed valve that allows gas to flow only in one direction from the crank chamber side to the breather chamber side, the reed valve being formed of: a valve seat formed on an end face of the inlet facing the breather chamber; a fixed stopper plate arranged so as to be opposed to and distanced form the valve seat; and an elastic valve plate fixed at one end thereof to the stopper plate and capable of bending elastically to change its position from a closed position to an opening limit position, the...

AI Technical Summary

Benefits of technology

[0007]The present invention has been made in consideration of such circumstances, and has an objective to provide a breather device for engine in which an elastic valve plate can be prevented from sticking to a stopper plate even if oil mist adheres to the elastic valve plate or the stopper plate of a reed valve.

[0009]According to the first feature of the present invention, when the elastic valve plate is pushed up against the stopper plate by positive pressure generated in the crank chamber, oil present between the elastic valve plate and a curved part is pushed out toward not only the peripheral edge part of the stopper, but also the oil discharge hole. Accordingly, the oil present between the elastic valve plate and the stopper plate can be reduced speedily and drastically. In addition, the presence of the oil discharge hole allows a small contact area between the elastic valve plate and the stopper plate. Accordingly, the elastic valve plate can be surely prevented from sticking to the stopper plate. Thereby, the elastic valve plate can have improved valve-closing responsiveness to speedily perform the closing-valve operation, and can close the inlet hole speedily and surely when the crank chamber is decompressed.

[0010]Moreover, the oil discharge hole plays another function of applying the pressure in the breather chamber to the elastic valve plate abutting against the stopper plate. Accordingly, when the crank chamber is decompressed, the elastic valve plate is biased toward the valve-closing side by the difference between the pressure in the crank chamber and the pressure in the breather chamber. The elastic valve plate can thus have valve-closing responsiveness improved further.

[0012]According to the second feature of the present invention, oil present between the elastic valve plate and the stopper plate can be reduced further speedily and drastically by pushing out the oil present between the elastic valve plate and the curved part toward the oil discharge hole and toward the paired oil discharge cutouts. Consequently, the elastic valve plate can be more surely prevented from sticking to the stopper plate.

[0014]According to the third feature of the present invention, the stopper plate can be prevented from having less rigidity because of the presence of the paired oil discharge cutouts. Thereby, the stopper plate can rigidly limit the position of the elastic valve plate at the opening limit position.

Problems solved by technology

Such oil mist adherence possibly causes the elastic valve plate to stick to the stopper plate when the elastic valve plate is brought to an opening limit position in which the elastic valve plate abuts against the stopper plate.

This might inhibit the closing operation of the elastic valve plate, which is to be performed when the crank chamber is decompressed.

As a result, the crank chamber cannot be kept under negative pressure.

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